This study is designed to explore and describe the hearing and auditory function of patients with xeroderma pigmentosa. Very little exists in the literature regarding cochlear or eighth nerve function in these patients who frequently develop hearing problems. Further, it is the express function of the Audiology Clinic in this study to monitor these subjects for ototoxic reactions to the drug 13-cis retinoic acid (for which they are enrolled in a study with NCI) over time. Twenty patients will be evaluated audiologically before, during and after administration of this medication and findings analyzed for significant changes. As of 1 May 1985, nine patients have been seen for baseline Audiologic Assessment.